1. Field of the Invention
This invention relates to an improvement in the method of manufacturing fine powders of metal halide.
2. Description of the Prior Art
Chromium chloride, chromium bromide, aluminum chloride, aluminum bromide, etc. are used for surface treatment, such as in chromium cementation; aluminum cementation; chromium evaporation and aluminium evaporation of steel products. These metal halides are also used as the materials for the manufacture of pure metallic powders of these metals.
For the manufacture of these metal halides, a wet system has generally been adopted so far. However, in the case of the wet system, since a hydrate is liable to be produced, it is difficult to obtain an anydrous metal halide. Also, since a metal halide containing moisture produces oxide upon the surface treatment of steel products, such a metal halide containing moisture cannot be employed for surface treatment of steel.
On the other hand, in the case of a dry system, for instance, chromium chloride can be manufactured by the reaction of hydrogen chloride gas with chromium as described below: EQU Cr + 2 HCl .fwdarw. CrCl.sub.2 + H.sub.2.
However, chromium chloride, when produced, assumes the shape of a needle or mass, and in order to make such chromium chloride into fine powders, these materials must be mechanically pulverized because chromium chloride has the properties of deliquescence. However, such pulverization is industrially difficult in operation and the obtaining of yields of chromium chloride powder in abundance is impossible.